Heading into the home stretch of the 2012 presidential race, Barack Obama is opening up a lead. Last week, Mitt Romney hit the accelerator and just about ran his campaign off a cliff.

All polls are snapshots, and the ones we’ve seen last week don’t reflect Romney’s ill-considered attack on the president as the ambassador lay dead and the Libyan embassy still smoldered. They reflect what the campaigns did this summer.

Some of the numbers most disturbing to the Romney camp come from their friends at Fox News. The Fox poll found Romney trailing by 5 percent nationally among likely voters. Obama leads by 14 points with women, 18 points with people who make under $50,000, 25 points with voters under 30. He holds solid leads with voters who care about foreign policy, education, Medicare, health care and terrorism.

This is no runaway contest, at least not yet. The Fox poll has the candidates tied on two critical questions: “taking the country in the right direction” and “improving the economy.” But the Democrats’ enthusiasm gap has disappeared, opinions have hardened and there are very few undecided or persuadable voters out there. In the swing state polls, the news for Romney is even worse.

There’s a reason these numbers have shifted. Take a step back and look at what the candidates needed to do in the phase of the campaign from the end of the primaries to Labor Day.

Obama had to fire up his base, so he endorsed gay marriage and enacted an executive order version of the Dream Act. By the time he got to his convention all was forgiven, with those two actions, along with the auto rescue, dominating the convention cheers in the pre-10 p.m. speeches.

Romney had to win the hearts of tea partiers and others who supported his opponents. He gave them Paul Ryan, which helped a little. Then he froze most of those who had dared challenge him in the primaries – Ron Paul, Michele Bachmann, Rick Perry, Herman Cain – out of the convention entirely. There was no rebellion in Tampa, but there was no love either.

Obama had to complete the job of defining Romney his primary opponents had begun. So his campaign went negative, hitting him hard on Bain and taxes. As he did, the election became more and more a choice, not a referendum.

Romney had to shore up his foreign policy credentials, but his stumbles on his trip to Europe and Jerusalem had the opposite effect.

Romney’s to-do list also included making himself more likeable, so one of the main themes of the GOP convention was what a warm, terrific human being he was. But that message was lost in some unplanned convention messages – the preening of Chris Christie, the prevarications of Paul Ryan and Clint Eastwood’s strange monolog.

Page 2 of 3 - Romney is still on thin ice with the loudest conservatives, some of whom spent the summer criticizing him for going too easy on Obama. Romney’s campaign understands he needs to win over independents and disillusioned Obama voters, so he took a softer, more-in-pity-than-anger tone in his acceptance speech.

But Romney hasn’t been able to bring out the Etch-A-Sketch when it came to policy, for fear of offending his right flank. He tried last weekend, saying on “Meet The Press” that he wanted to keep some elements of health care reform, including the requirement that insurers to cover pre-existing conditions. But within hours his campaign was in full retreat back to their “full repeal” position.

Meanwhile, Romney has been unwilling, unable or unprepared to answer the most obvious questions about his taxes, the abortion plank in the GOP platform and the details of his deficit-reduction plan. They wouldn’t even have to be great, coherent answers, but with all the money and talent in his campaign, you’d think they would have figured out some responses last spring.

Romney made another unforced error by leaving foreign policy, the war in Afghanistan and American troops out of the Tampa convention. It was a mistake Democrats took full advantage of in Charlotte, stopping just short of parading around the hall with Osama bin Laden’s head on a pike.

Romney doubled-down on that mistake, reinforcing the foreign policy shakiness he showed in Europe. With his over-eager, shoot-from-the-hip response to the attack in Libya, he made things immeasurably worse. He looks inexperienced and rash. Obama looks careful and cool.

The pundits this week were arguing whether Romney’s eruption after the Libya attack would be seen as this campaign’s “Lehman Brothers moment,” referring to the time four years ago when Wall Street crashed and John McCain flailed, shutting down his campaign, calling for the debates to be postponed and otherwise losing it.

Obama declined to delay the debate, explaining that a president needed to be able to do more than one thing at once. When leaders of both parties gathered for a summit meeting at the White House that McCain had demanded, it was Obama who seemed in control, presenting the Democrats’ position, leading the way to consensus, while McCain, according to news accounts, had nothing to say.

Whether or not this marks a comparable turning point, time will tell. But that is not the kind of question Team Romney would have hoped was on people’s minds six weeks before the election.

Romney may regain his footing, but there’s not much evidence in his past performance that he can elevate his game in Clintonian comeback-kid fashion. He won the GOP nomination mostly by having the most money to spend on negative TV ads, and he’s got the warchest to try that again in the general election.

Page 3 of 3 - But time runs short, voters’ minds are made up, and Republicans and conservative media types are already turning on the candidate they didn’t like from the beginning. It feels like things may be unraveling for Mitt Romney.

Rick Holmes, opinion editor for the MetroWest (Mass.) Daily News, blogs at Holmes & Co. He can be reached at rholmes@wickedlocal.com.